MOSCOW — A meteor that scientists estimate weighed 10 tons today streaked at supersonic speed over Russia’s Ural Mountains, setting off blasts that injured 500 people and frightened countless more. The Russian Academy of Sciences said that the meteor over the Chelyabinsk region entered the Earth’s atmosphere at a speed of at least 33,000 mph and shattered about 18 to 32 miles above ground. The fall caused explosions that broke glass over a wide area. The Emergency Ministry says more than 500 people sought treatment after the blasts and that 34 of them were hospitalized. Some fragments fell in a reservoir outside the town of Cherbakul, the regional governor’s office said, according to the ITAR-Tass news agency. It was not immediately clear if any people were struck by fragments. A 20-foot-wide crater was found in the same area which could be the result of fragments striking the ground.